Lesson 1/Learning Event 2
Learning Event 2:
SKYWAVES.
1.
Early radio communication was thought to be impossible over long
distances.
The reasoning, local terrain would absorb the radio
signal.
When trans-atlantic communication was accomplished, this
opened up new questions.
If the surface wave was limited, then how
did communication take place? The conclusion made was that the earth
was surrounded by something other than air.
Two men, one an
Englishman the other an American, suggested that a electrified layer
above the earth reflected radio signals.
Later experiments showed
that more than one layer existed.
2.
Formation of the Ionosphere: As shown in figure 2 the earth's
atmosphere extends up to a distance of 250 miles.
The level of
ionization increases with height.
The sun's rays combined with
cosmic rays ionize these layers.
a. Ionization.
The bombardment by the sun and ultraviolet rays
charge the atoms in these layers. This action is called ionization.
b. Recombination. As the sun goes down and the intensity of the
ultraviolet rays decreases, the ionization of the layers decreases.
Just before sunrise, ionization is at its lowest point.
c. Source of ionization - the sun.
The earth and the sun are
composed of the same basic elements.
The violent state of these
elements on the sun keeps it in a constant of state of molten or
gaseous condition.
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